Fuel and process for preparaing same



Patented Mar. 3, 1953 FUEL AND PROCESS FOR PREPARING SAME Lloyd C. Fetterly, Seattle, Wash., assignor to Shell Development Company, San Francisco, Calif., ai corporation of Delaware Application April 30, 1948, Serial No. 24,123

Claims.

This invention is concerned with fuel compositions designed especially for, use at extremely low temperatures. More particularly,this invention is directed to fueloils or compositions suitable for use in jet engines and in diesel engines, especially under arctic conditions.

The fuels presently available in substantial a-mounts are suitable for use only under operating conditions normally encountered in the more temperate climates. Fuels which are suitable for use in jet-propelled aircraft or in dieselpowered equipment have heretofore been limited by the inherent characteristics which they necessarily possessed, due to the mixture of components present therein, While artificially blended fuels have been prepared from time to time, which fuels have properties which permit their use under low operating temperatures, these have been mere laboratory curiosities since it has heretofore been impossible to produce them in any effective quantities. In the event of a national emergency and due to the rapid development of jet engines, an enormous demand may be expected to develop for jet and diesel-engine fuels for use under frigid conditions.

The most serious shortcoming of the usual jet and diesel fuels, when low operating conditions must be considered, is their low temperature susceptibility. The high pour point of the fuel stocks available precludes their use at temperatures substantially below about -30" F; however, it has been recently recognized that thepour point of a given material is not strictly indicative of its performance at low operating temperatures. It has been found that if stocks of a given pour point are held at about their low pour temperature (even above their pour points), certain components therein eventually commence to crystallize. This becomes apparent by the appearance of a cloud or haze in the fuel. Under more stringent temperature conditions, the fuel eventually solidies or freezes.

Even at the temperatures at which the cloud first appears, i. e., the cloud point, the technical consequences commence to become extremely serious. Jet and diesel engines, the fuel lines of which are exposed for any substantial period to temperatures below the cloud-point temperature of the fuel contained in said lines, will be found to be impossible to operate due to plugging of the lines because of components which have crystallized therein from the fuel. A more sensitive but necessary part of jet engines is the filter, through which all the fuel must pass from the feed line into the combustion chamber. Any crystallization of fuel components will rapidly cause this filter to become clogged, thus cutting off the fuel supply to the engine.

While the pour point of some fuel stocks is related in a general way to the cloud point and freezing point thereof, this relationship is neither universal nor uniform. Some stocks which have relatively low pour points have been found unsuitable for use in cold climates because of their unaccountably poor cloud points.

An effort to overcome these difficulties has been made by employing more volatile fuels having lower pour points. Y In such circumstances, however, it has been `found that the fuels are relatively volatile and, consequently, are a fire hazard, particularly when used in various aircraft engines. y

The conventional methods for the preparation of fuels from petroleum sources do not permit the ypreparation of fuels having suitable properties for use under frigid conditions. It is Well known that petroleum distillates contain a number of types of configurations, including substantially straight-chained paraffin hydrocarbons, isoparaflins, naphthenes and aromatics. If the fuels are prepared from cracked stocks, the mixtures of hydrocarbons also contain acyclic unsaturated materials such as olefins. Fractional distillation, the normal means of treating petroleum stocks, has substantially no effect upon the composition of the distillate except in regard to boiling point. Therefore, any of the distillates may, and usually do, contain a mixture of all of the components listed above.

As pointed out hereinbefore, these heterogeneous fuel mixtures are unsuitable for use in cold climates because of one or more components present in the fuel. Probably the Worst offenders in this regard are the substantially unbranched hydrocarbons, hereinafter referred to as the normal hydrocarbons. Another class of constituents of the usual fuels which tends to have adverse operating characteristics includes the aromatics, since these have relatively poor cetane numbers.

' telluourea.

aeecfios 3 Recently a method has been developed for the fractionation of mixtures of organic compounds according to structural type. As more partic" larly described hereinafter, this method c mprises treatment of the mixture with a complesforming agent having the general con'guration:

wherein X is an element selected from the righthand side of groups 6 of the periodic table, and preferably having an atomic 'Weight of less than about 128. Compounds falling within this cl include especially urea, thiourea, selenourea a Also, the acid salts ofvthese pounds, such as the hydrochlorides oil acetates, are `suitable as the complex-forming agents. The complexes appear to fall within the 'general classification known as clathrate compounds."

about 660 F. It has also been found that the' mixture of non-normal hydrocarbons boiling within the range MEW-650 F. may be used Without substantial lnodication as an arctic diesel or jet engine fuel, even in the absence of the above-mentioned lower-boiling normal hydrocarbons.

A still more highly preferred fuel for use under arctic conditions comprises the combination of a relatively minor amount of normal hydrocarbons boiling Within the range 275 l25 F. and of a major amount of isopararlins and/or naphthenes boiling Within the range lil5"-660 F., said composition containing no appreciablearnounts of aromatics.

Again in accordance with this invention, it has been found that fuels such as those described above may be prepared by use of the extractive crystallization methods referred to hereinbefore.. One of such i -ethods comprises the treatment of .a petroleumdistillate having a boiling range It has been found that fractionation by means Y be substantially inert toward normal (straight- 'c`:ha'i'n`ed) compounds and aromatics. Selenourea has a more general complex-forming action and appears 'to form crystalline complexes with a Wide variety of structural 'congurationa Up to the present time, this method has been used simply Vfor the separation of a particular fraction from Vits mixtures. No particular use -h'a-s been advanced for the raflinate in any instance. Throughout the-present specification and Furthermore, it has been noted that olaiins, the 'term rafnatei will refer to thatg;

'portion of Vainiiiture of organic compounds which is substantially inert toward a complex-forming agent under the conditions employed. The terni extract is-meant to include that portion "of 'the viniiiture' of organic compounds forming a;

complex -with the agent and thereby `extracted from "the mixture.

It is 4an object of the present invention to `provide a novel fuel especially suitable for use under Yfrigid V(very low temperature) operating conditions. tion t0 providea fuel particularly designed for use in jet engines and diesel engines. it is a further object to provide a method for the prepvfaration of Yfuels having desirably low clouc points and freezing points. It is still another object to provide la method vfor the preparation 'of l'a blended `fuel having improved loweteinperature startability as Well as superior vlow-temperature operating characteristics. Other objects Vwill become apparent during the following discussion.

. Now, in accordance vvith this invention, it .has ybeen found thata highly improved fuel, especially `suitable for use under frigid operating condi- "tions, comprises 'a minor amountof substantially 'normal hydrocarbons boiling Within the Vrange of fror'nabou't 275 F. :to about 425 F., vblended with amaj'or proportion of substantially non-normal V(i. e., non-straight-chained) hydrocarbons boiling within the range of from about 415 to It is another object of this invenespecially if they are hydrogenated within the limits tiff-@69 F. with a complexforming Vagent such as urea, whereby the nor mal hydrocarbons are extracted from the distillate. rhe rafiinate's so produced have been found to have exceptionallyrlow cloud and freezing points and to be suitable Without substantial modincation for use as a 'fuel under frigid conditions.

An improvement upon said fuel comprises the separate treatment of a petroleum distillate havingaboiling range Within the limits 275-425 E. with a complex-forming agent such as urea for the purpose v-of separating the substantially normal hydrocarbons therefrom. minor amount ofthe-hydrocarbons extracted is combined with a major proportion of the iirst hydrocarbon Iraffinate for the preparation of an arctic diesel or jet fuel having the added property of improved startability and a higher cetane I number.

A. still greater 'improvement 'in the basic fuel may be effected by treatment of the rainate aient, for 'the pu 'pose 'of 'removing therefrom at least Ia large proportion ofl the 'aromatics. line optimum fuel, therefore,` comprises' a mixture of 545% normal' 4paramns boiling Within the range Ziff-425 FQ and atleast of a ture of isoparaffins and'naplithenes boiling Within the range ily-"56e" E, 'Heretofore it has been limpossible to produce such a fuel except on a very small scale, completely inadequate for practical us'e.

YThe stocks to be treated in accordance with the present invention are preferably straightrun distillates since they contain .ctically no oleins.' However, cracked stocks may be used,

for the purns. The

pose of convertingvth'e "oi'eiins to p stocls may be "prepared or 'moe any the normal conversion'procedures'such as alkyl-ation, hydro-forming or similar procedures. in thecase of theblended fuel described aboveit is preferable to choose t1 'o' stocks; the iiret ci which has a high normal paraffin content ivhile the higher-boiling stool; has a relatively high pro-V portion of isoparainsor naphthenes.

The process of the-present invention comprises treatment of the selected. stock with the 'complexforrning agent, separation ofthe complexes so formed-from the unaffected portions of the sterk.' and utleetgg- 0f. the flammes s@ Pl'odu@ Typical procedures illustrating'the various alfor other purposes. mal hydrocarbons Il are transferred to a re- A generator I3, preferably together with a suitable "ternatives which may be employed are outlined in the accompanying diagram. In the diagram the term heavy distillate feed refers to a petroleum distillate falling within the range 415-660 F. The term light distillate feed refers to a petroleum distillate falling within the range 275- 425 F. As shown in the diagram, the heavy distillate feed I enters a reactor 2 together with urea E. Under the conditions to be described hereinafter, crystalline complexes are formed between urea and the normal hydrocarbon portion of the distillate. The slurry containing the crystalline complexes and the remaining liquid portions of the reaction mixture are sent to a separator 3, wherein the crystalline complexes are separated from the liquid components by normal hydrocarbon products as follows:

The light distillate feed 'I is treated with urea 6 in a similar reactor 8 to produce a slurry containing urea complexes of the normal hydrocarbons suspended in the liquid components which are not affected. The slurry is conducted to separator 9 where the liquid isoparaflins and cyclic hydrocarbons I are removed and utilized The complexes of the norquantity of water I2. The complexes, when heated in the presence of water, decompose and i thus permit regeneration of the light normal hydrocarbons I therefrom. The urea simultaneously regenerated dissolves in the water which is present and separates from the hydrocarbons in the form of an aqueous solution. For the purpose of producing the blended jet fuel described hereinbefore, a minor amount of the light normal hydrocarbons I5 is combined with the heavy non-normal hydrocarbons 5 to give the blend I6.

Two alternative procedures also are illustrated in the diagram. The heavy non-normal hydrocarbons 5 may be combined with light normal hydrocarbons producedlin the following manner: A light distillate feed I 'l is treated with thiourea I8 in a reactorV I9.

The isoparaiin and naphthene porti-ons of the feed form complexes with thiourea, while the substantially normal hydrocarbons are not affected. The slurry so produced is conducted to a separator wherein the unwanted thiourea complexes 2l are separated 'f from the desired liquid normal hydrocarbons 22.

The latter are then combined in their proper proportion with the heavy non-normal hydrocarbons 5 to give the blended fuel 23.

The choice of the complex-forming agent to be employed will depend, in a major extent, upon the feed to be treated. At times it is advantageous to isolate the heavy non-normal fraction by a thiourea treatment as follows: The heavy distillate feed 24 is treated with thiourea 25 in a reactor 2B. The mixture so produced is conducted to a separator 21, wherein the unaifected normal hydrocarbons 28 are separated from the thiourea complexes of isoparains and naphthenes 29. The complexes are conducted to a regenerator 3|, where they are mixed with water 30 and heated to the decomposition temperature. The thiourea regenerated from the complexes by this-treatment dissolves in the water and is rel moved in therform4 of. a solution32.. AThe regen-sl amount of aromatic hydrocarbons. preferably, the boiling range of the hydrocar bons should be within the range 425-65\0 F. It

erated heavy isoparaiiins and naphthenes 33 may vention comprises at least about 85% of a mixture of non-normal hydrocarbons having a boiling range within the limits 415660 F. This fuel comprises isoparains and/or naphthenes i and may contain a minor proportion of aromatics within the same boiling range. Preferably, however, the stock contains a minimum Still more has been found that such a mixture has the unexpected advantage of remaining completely iiuid at temperatures lower than 76 F. as indicated by both the pour and cloud points. Similar stocks containing the unbranched parafns normally present are found to have cloud points as high as from 5 to +10 F., respectively. While the hydrocarbons are preferably isolated from petroleum distillates, they may be obtained from other large-volume sources such :as polymerized hydrocarbon gases or from synthetic coal hydrocarbons.

In the preparation of fuels having improved startability at low temperatures, the normal hydrocarbons to be added to the above fuel should comprise 5-15% by volume having a boiling range within the limits 275-425 F. More preferably, however, the normal hydrocarbons should boil within the range 30W-40G F. An optimum blend is obtained when the composition contains a minimum of 10% of the described normal hydrocarbons together with at least 85% cf the isoparaiiins or naphthenes discussed above. Fuels for use at extremely low temperatures should be Vmodified by the addition of correspondingly greater amounts of the lower-boiling normal hydrocarbons.

It has been discovered that the blends described above have a characteristic of prime importance in jet-engine operation: The lean blow)- out characteristics have been found to be highly satisfactory as compared with other fuels containing a higher proportion of normal paraiiins, even though the boiling range of the other blends is similar. Optimum lean blow-out characteristics will vary with the airspeed and with the operating altitude, but it has been noted that the present fuel shows little susceptibility to change under these two variables.

The fuels described may be modified by the addition of suitable improving agents such as amyl nitrate or ditertiary butyl peroxide for the improvement of cetane number. Viscosity index limproving agents also may be added, such as l ployed if desired, such as para-phenylene di alcoholic in character.

amine. However, the proportion of such addin tives should be held to a minimum so that combustion residues will not be unduly large.

In the preparation of the present fuels by extractive crystallization, advantage may be taken of numerous operating conditions. For example, the complex-forming agent may be used in the form of a solid or of a solution. The preferred solvent is one which is largely aqueous or aqueous The alcohols which may L be employed include .especially the lower alcohols,

such as methyl and ethyl alcohol., .,The agent Vor 7 solution .thereof should be present in the reactor l` substantial excess of the amount necessary for maximum complex formation.

It has been found that the extent of sucht-formation is dependent, in part, upon the Aconcentration Aof the complex-,forming agent in its solvent. In order to maintain a high deg-ree of complex formation, the solution of the agent should be kept near the saturation point at all times. However., :circumstances :may arise where the maxirnum complex orma-.tion would be undesirable. For example, a stock having an init-ial boiling vpoint below tneminimum desiredinoy be treated .such a way as to permit only the higher Amolecular'weishthydrocarbonsto ,form crystalline complexes. 'This is eilectedfby adjusting the concentration tne complex-,forming agent `in its soivent .so `as to permit selective formation. lt has been vnoted that each hydrocarbon requires a critical minimum concentration of the agent for any .given temperature before complex fcinnation is possible. Hence, by adjusting the concentration ci the .agent -to a point below this `critical minimum for the lighter hydrocarbons present, it is v.pcssiblerto.cause the heavier hydrocarbons to form 4crystallirne complexes while the Vlighter 'ma- :terials are unaiected.

The mixtures of hydrocarbons to be treated may vbe contacted with the complex-forming agent without substantial modication or, if it is desired, inthe form of a Vdiluted solution. -The diluent for the hydrocarbon mixture should be one which is substantially inert toward the complex-forming agent under the conditions employed. A suitable non-polar solvent for ythis purpose is pentane, which may be used .at the usual temperatures at which complex formation is carried out. Certain polar solvents have been found particularly suitable due to their special solubility characteristics. Methyl isobutyl ketone is a particularly .outstanding example oi this type ci medium. It has lbeen found that this solvent permits optimum crystal structure inthe complex allows the formation to proceed at a max- `rate. lThese .properties appear to be due to the fact that the .solvent is completely rniscible petroleum fraction in addition thereto,`dissolves to a certain ent in the aqueous solution or `the complex-.forming agent which `is used. Methyl isobutyl 'ketone maybe employed when urea is the complex-forming agent. At low temperatures .the solvent will form a complex with thiourea, apparently clue to` its isoallryl substituents. it is preferred practice to use methyl ethyl ketone as the solvent medium when thiourea is present as the complex-forming agent. IThis material appears to be substantially inert toward thiourea, probably because oi its unbranched allryl groups.

A special group of solvents Whichmay be profitably employed in the present process comprises those which will dissolve both the complex-forming agent and simultaneously extract the aromatic fraction from thepetroleum distillate which is being treated. A suitable solvent ci this type is liquid sulfur dioxide. In effect, the use of this type Voi medium enables what may be regarded. as a combined Edeleanu treatment and an extractive crystallization treatment. This is particularly desirable when it ,is preferred to eliminate aromatics from-the iuel'being prepared.

`ihe agent andthe petroleum distillate are `norreally contacted by rapid mixing at about room perature or below. Higher temperatures may `8 .be employed as the molecular weight .of the hydrocarbons is increased. A continuous process of complex formation has been found especially effective as opposed to a batch process.

The crystalline complexes are usually formed after a period of apparent inactivity. The period between initial contact of the agent and the hydrocarbons before the lirst crystals become apparent is usually called the induction period. This period may be only a matter of seconds but, at times, may be as long as several minutes or even as much as two to four hours. The combination of high agent concentration and low reaction temperature encourages short induction periods Once the complex has commenced to form, the reaction appears to proceed rapidly to completion. if a large amount of the complex is formed relative to the amount of the liquid components prosent, the reaction mixture may be diicult to handle; hence, it is advisable to maintain vat least a sufficient amount ci liquid components in the reaction mixture to enable facility in transporting and otherwise handling the material.

The design of the reactor should be such as to permit the hydrocarbon feed and the complexiorming agent to be introduced at the bottom thereof and to continuously now upwards in Such a. manner that the reaction is complete at the exit near the top. The take-ofi" is led to a separation area wherein the crystalline complexes are separated from the liquid components of the reaction mixture. Suitable methods of separation comprise basket oentrifuges or rotary filters. The complexes may be puried to a certain extent by washing with a selective solvent such as pentane. This step has been found to be of some importance since the surfaces of the crystals are easily wet oy the liquid hydrocarbons present. n order to obtain clean fractionation and to avoid contamination oi' the complexes by the remaining liquid fractions, the washing step appears to be particularly desirable.

The crystalline complexes have been separated from the liquid fraction of the distillate, the step remains of regenerating hydrocarbons therefrom. The regeneration preferably comprises the application or" heat, preferably in the presence 0f a solvent, either for the hydrocarbons or for the complex-forming agent. For example, if a crystalline complex of a normal hydrocarbon and urea is heated in the presence of water to a temperature above about C., the complex decomposes to yield the hydrocarbon and the complex-forming agent. The latter dissolves in the water which is present and forms a solution which is immiscible with the hydrocarbon. Alternatively, a dilute solution of the complexforming agent may be heated with the complexes. Under these circumstances, the complex decomposes to yield the regenerated hydrocarbon and a solution of the agent whose concentration has been incurred by the addition of the regenerated complex-forming agent. The augmented solution may be used subsequently in the formation of additional complexes.

The arctic diesel or jet fuels which may be prepared by the method of the present invention will have the following critical characteristics:

Cloud point, l?! maximum -75 Freezing point, E., maximum -76 Viscosity centistokes at -65 F., maximum 50 Viscosity centistokes at F., minimu1n 0.7

ASTM initial boiling point, F., minimum 275 ASTM nal boiling point. E., maximum.. 660

The process o'f the present invention may be illustrated by the following example:

A 50` cetane diesel fuel was prepared by Edeleanu treatment of a fraction of a Los Angeles basin crude, the fraction boiling between 415 F. and 66H F. rf'he raiiinate from said treatment, which constituted the diesel fuel, contained aromatics 13.5% straight-chain hydrocarbons, the remainder being a mixture of branched-chain hydrocarbons and naphthenes.

l The rainate described above was diluted with an equal volume of methyl isobutyl ketone and mixed at 70 F. with a saturated aqueous solution of urea. The crystalline complexeswhich formed between the straight-chain hydrocarbons and urea were removed by filtration, leaving a raihnate containing less than 1% straight-chain hydrocarbons and having the following properties:

Cetane number 45 Viscosity, centistokes at 100 F 3.1 Viscosity, centistokes at 65 F 299 Initial boiling point, F 415 Final boiling point, F 659 Pour point, F lower than -76 Cloud point, F lower than n'76 I claim as my invention:

1. The method of operating an aircraft turbine engine which comprises burning therein a fuel having 5-15% substantially normal hydrocarbons with a boiling range within the limits 275-425 F., and at least 85% of substantially non-normal hydrocarbons with a boiling range within the limits 415-560 F.

2. The process for the preparation of an engine fuel having improved startability, high endpoint and low pour point comprising separately treating two petroleum distillates, the first of which has a boiling range within the limits 275-425 F., and the second of which has a boiling range within the limits 415-660 F., with at least one complex-forming agent having the general configuration wherein X is an element selected from the righthand side of group VI of the periodic table, whereby complexes are formed between the agent and a fraction of each distillate, said complex formation in each case causing separation of normal hydrocarbons of each distillate 'from the nonnormal fractions thereof, and subsequently blend" ing 5-15% of the substantially normal hydrocarbons of the first distillate with 85-95% of the non-normal hydrocarbons of the second distillate.

3. A novel engine fuel having improved starte.- bility, high end-point and low pour point consisting essentially of 5-15% of substantially normal hydrocarbons having a boiling range within the limits 275-425 F., and 85-95% of substantially non-normal hydrocarbons having a boiling range within the limits 415-660 F.

4. A fuel composition according to claim 3, wherein a preponderant proportion of the nonnormal hydrocarbons are isoparans and naph thenes.

5. The process which comprises separately contacting urea with two petroleum distillates, the rst of which has a boiling range within the limits 275-425 F., and the second of which has a boiling range within the limits 4l5660 F.,

whereby crystalline urea complexes of the substantially normal hydrocarbons present in each distillate are formed, the non-normal fractions thereof being unaffected, separating said complexes from the non-normal fractions, regenerating the normal hydrocarbons of the first distillate from their urea complexes, and blending said regenerated normal hydrocarbons with the nonnormal hydrocarbons of said second fraction, so that the resulting blend contains 5-l5% of normal hydrocarbons.

6. A novel engine fuel having a high end-point and a low pour point comprising a straight-run stove oil having a boiling range within the limits 415 F.-660 F. being substantially free from A straight-chain hydrocarbons, said fuel having a poul` point substantially below about -30 F.

7. A novel jet-engine fuel having improved startability, high end-point and low pour point consisting essentially oi 5-15% of substantially straight-chain hydrocarbons obtained from straight-run gasoline having a boiling range within the limits 275 F.425 F., together with 95% of a straight-run petroleum distillate having a boiling range within the limits 415 F.- 660" F., from which the substantially straightchain hydrocarbons have been removed.

8. The process for the preparation of novel engine fuels comp-rising contacting a straight-run petroleum distillate having a boiling range within the limits 415S60 F. with liquid sulfur dioxide to produce an extract phase and a raffinate phase, contacting said raffinate phase with urea whereby the substantially normal hydrocarbons present therein form crystalline urea complexes, separating said complexes from the remaining liquid fraction of said raflinate and blending the remaining liquid fraction with normal hydrocarbons obtained by urea extraction of a petroleum distillate having a boiling range within the limits 275-425 F. so that the resulting blend contains 5-i5% of normal hydrocarbons.

9. The process which comprises contacting a first petroleum distillate having a boiling range within the limits 275-425 F. and having a high normal paraffin content with thiourea, whereby the non-normal hydrocarbons present therein form crystalline thiourea complexes, separating said thiourea complexes from the substantially normal hydrocarbons of the first distillate, contacting a second petroleum distillate having a boiling range within the limits 415-560 F.. and having a relatively high proportion of isoparaflins and naphthenes with urea, whereby the substantially normal hydrocarbons present therein form crystalline urea complexes, separating said urea complexes from the isoparafns and naphthenes of the second distillate, and blending the normal hydrocarbons of the first distillate with the isoparaffins and naphthenes of the second distillate so that the resulting blend contains 5-15% of normal hydrocarbons.

10. A novel engine fuel having improved startability, high end-point and low pour point consisting essentially of 515% of substantially normal hydrocarbons having a boiling range within the limits 30W-400 F., and 8595% of substantially non-normal hydrocarbons having a boiling range within the limits 425-650 F.

LLOYD C. FETTERLY.

(References on following page) 1 I` REFERENCES CITED The following references are of record in .the le of this patent:

UNITED STATES PATENTS Number 5 Name VDate Black Dec. 24, 1935 Howard July 28, 1936 MacKenzie Aug. 17, 1937 Voorhees Oct. 19, 1937 10 Risk Mar. 2, 1943 Pevere Oct. 24, 1944 Bolt et al Oct. 24, 1944 Cloud Jan. 2, 1945 Davis July 2, 1946 15 Zwicky et al Jan. 6, 1948 `OTHER REFERENCES.

emhenen,v Chemical ,Constitutents of Petrole* um. pp. 201, A230, 231, 232. 'Published in 1945 by Reinhold Publishing Corp., N. Y., N. Y.

Technical Oil Mission, Reel 143, `6 page translation of German .patent application No. B190, 197, deposited in the Library of Congress May 22, 1946.

Petroleum Engineer, Aug. 1948, pp. 177, 180, 182, 185, 186.l Article by H. A. Murray, presented before Texas Mid-Continent Oil and Gas Association 28th Annual Meeting, San Antonio, Texas, Oct. 17, 1947. 

2. THE PROCESS FOR THE PREPARATION OF AN ENGINE FUEL HAVING IMPROVED STARTABILITY, HIGH ENDPOINT AND LOW POUR POINT COMPRISING SEPARATELY TREATING TWO PETROLEUM DISTILLATES, THE FIRST OF WHICH HAS A BOILING RANGE WITHIN THE LIMITS 275*-425* F., AND THE SECOND OF WHICH HAS A BOILING RANGE WITHIN THE LIMITS 415*-660* F., WITH AT LEAST ONE COMPLEX-FORMING AGENT HAVING THE GENERAL CONFIGURATION
 3. A NOVEL ENGING FUEL HAVING IMPROVED STARTABILITY, HIGH END-POINT AND LOW POUR POINT CONSISTING ESSENTIALLY OF 5-15% OF SUBSTANTIALLY NORMAL HYDROCARBONS HAVING A BOILING RANGE WITHIN THE LIMITS 275*-425* F., AND 85-95% OF SUBSTANTIALLY NON-NORMAL HYDROCARBONS HAVING A BOILING RANGE WITHIN THE LIMITS 415*-660* F. 